Conventionally, there has been a proposal to employ a Rankine cycle in a vehicle in order to recover waste heat from an engine and thereby improve the fuel economy, as described in, for example, Japanese patent application Kokai publication No. 11-51582 (Patent Literature 1). For example, engine-main-body cooling water heated by an engine main body is used as a heating source of a Rankine cycle while intercooler cooling water cooled by a sub-radiator is used as a cooling source, so that a temperature difference between these flows of cooling water can be recovered as a power in a compressor (turbine).
However, when such a Rankine cycle is employed on a vehicle, the vehicle weight is increased. This may counterbalance the effect of improving the fuel economy.
On the other hand, the above-described engine-main-body cooling water and intercooler cooling water are air-cooled respectively in a radiator and a sub-radiator, which are disposed at a front surface of a vehicle. However, since a condenser for an air conditioner is disposed in front of the radiator and the sub-radiator, the condenser blocks vehicle-speed wind from flowing through the vehicle. Hence, the Rankine cycle may not be provided with cooling water having a sufficient temperature difference.